Multi-chambered arc interrupter having fluid pump



M June '20, 1967 E, W STON 3,327,083

MULTI-CHAMBERED ARC INTERRUPTER HAVING FLUID PUMP Filed Dec. 7, 1964 United States Patent 3,327,083 MULTI-CHAMBERED ARC INTERRUPTER HAVING FLUID PUMP Donald E. Weston, Cudahy, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis. Filed Dec. 7, 1964, Ser. No. 416,554 4 Claims. (Cl. 200-150) ABSTRACT OF THE DISCLOSURE A load break switch comprises an oil filled insulated housing in which an arc interrupter and a piston type oil pump are located. The are interrupter is divided into two interconnected chambers and a stationary contact is located in one chamber. The stationary contact operates a valve which controls communication between the said one chamber and the oil filled housing. A bayonet type movable contact extends through the other chamber and is movable into and out of the said one chamber. When the movable contact engages the stationary contact, the valve is held open. But when disengagement occurs and an arc is formed, the valve closes and oil is pumped through the other chamber. Y

This invention relates to are interrupters used in fluid filled electric circuit interrupting devices such as load break switches and circuit breakers to interrupt the are formed as the contacts separate.

Load break switches, for example, are used in power systems to connect and disconnect electrical equipment to and from an electrical power source and are, for example, adapted to interrupt currents ranging from 500 to 5000 amperes at 138 kv. Usually, one such switch is provided for each phase line in a multiphase alternating current power system. One type of load break switch comprises an insulating housing which is filled with an arc interrupting fluid such as a body of oil. At least one pair of separable contacts are located within an arc interrupter which is submerged in the body of oil. A pump operated by the same means that effects contact separation causes oil to flow through the arc interrupter during contact separation to aid in arc extinguishment.

It is an object of the present invention to provide improved arc interrupters for fluid filled circuits interrupting devices.

Another object is to provide improved arc interrupters of the aforesaid character which more efiective-ly use the fluid available for are extinguishment.

Another object is to provide improved arc interrupters of the aforesaid character which more efiectively utilize the Vapor pressure developed in the fluid during arcing to aid in extinguishing the arc.

Another object is to provide improved fluid filled circuit interrupting devices, such as load break switches, which have increased dielectric strength during interrupting operations and which have the capacity to handle higher voltage and current values.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates a preferred embodiment of the invention but it is to be understood that the embodiment illustrated is susceptible of modifications with respect to details thereof without departing from the scope of the appended claims.

In the drawing:

FIG. 1 is an elevational view of a load break switch incorporating the present invention;

FIG. 2 is an enlarged view, partly in section of a portion of the interior of the switch of FIG. 1;

3,327,083 Patented June 20, 1967 "ice FIG. 3 is a sectional view of the portion of the switch shown in FIG. 2 taken along the line IIIIII; and

FIG. 4 is a schematic showing of the electrical connections within the load break switch of FIG. 1.

Referring to FIG. 1 of the drawing, there is shown the exterior of a load break switch incorporating the present invention and comprising a hollow electrical insulating housing 10 which is understood to be filled with an arc extinguishing fluid or media such as a body of oil. Housing 10 is provided at its lower end with an electrically conductive supporting base 12 which seals the housing and serves as an electrical connection to a stationary contact, hereinafter described, within the housing. Housing 10 is provided at its upper end with an electrically conductive shell or dome 14 which seals the upper end of the housing and serves as an electrical connection to a movable contact, hereinafter described, within the housing. Dome 14 is understood to house operating mechanism (not shown) which effects movement of the movable contacts within housing 10 to open and closed position and which also effects operation of means for effecting oil circulation through an-arc formed during a contact opening operation.

Referring to FIGS. 2 and 3, base 12 of the load break switch is provided within housing 10 with a flanged socket 16 for rigidly supporting a hollow cylindrical tube 18 made of insulating material. A piston 20 is located within tube 18 and cooperates there-with to provide an oil pump. Piston 20 is connected to a reciprocally movable rod 22 which is understood to be connected to and movable by the operating mechanism (not shown) in dome 14 of the load break switch.

A contact support bracket 24 is rigidly connected to and movable with rod 22. Bracket 24 rigidly supports three radially arranged downwardly depending electrically conductive bayonet type contacts 26, 28 and 30. The bayonet contacts are electrically insulated from rod 22 and from each other, except as hereinafter explained.

Tube 18 is provided with spaced apart upper and lower insulating plates 32 and 34, respectively, which cooperate with three radially arranged hollow cylindrical insulating tubes 36, 38 and located therebetween to provide the casings of three arc interrupters 42, 44 and 46.

The plates 32 and 34 are held in position on tube 18 and clamped against the tubes 36, 38 and 40 by means of three tie rods 48. As FIG. 2 shows, an insulating spacer is provided on each tie rid 48 between the flangeof socket 16 and lower plate 34. Upper plate 32 supports a hollow cylindrical housing Which shields rod 22, bracket 24 and the upper portion of the movable contacts 26, 28 and 30.

Since the interrupters 42, 44 and 46 are identical to each other, a detailed description of interrupter 42 is to be understood as applicable to the other two. As FIG. 2 shows, tube 36 of interrupter 42 is closed at its ends by the plates 32 and 34 and is divided into two chambers 54 and 56 by means such as a partition 58 which has a hole 60 therein for accommodating movable contact 26. Upper plate 32 is provided with three holes 52, each of which accommodates a movable contact 26, 28 or 30 which extends into its respective interrupter.

Means are provided to permit a flow of oil through one of the two chambers during contact opening. Thus the first or upper chamber 56 of the casing of interrupter 42 communicates with the interior of tube 18 by means of a fluid input orifice 62. Casing 36 is also provided with a fluid exhaust orifice 64 which communicates between upper chamber 56 and the interior of housing 10. Battle plates 66 understood to be suitably supported by casing 36 are located adjacent exhaust orifice 64. During the upward stroke of piston 20, oil is forced from the interior of tube 18, through input orifice 62, chamber 56 of interlower plate 34 in registry with a hole 76 in the lower plate.

Ari electrically conductive contact member 78 is slidably mounted in guide '72 and is rigidly secured to one end of an electrically conductive member 80 which serves as a valve stem. Contact member 78 is adapted to engage the end of movable contact 26 when the latter is in contact closed position. Member 80 extends through hole 76 in lower plate 34 to the exterior of interrupter 42. A disk shaped valve plate 82 having an annular sealing ring 84 on its face is rigidly secured to valve stem member 80. Biasing means are provided to effect movement of valve 82 to close orifice 68 when the contacts open. The biasing means take the form of a compression spring 86 which is located in guide 72 between contact 78 and lower plate 34. When movable contact 26 is in fully closed position it bears against contact 78 to depress the latter in guide 72, to cause compression of spring 86, and to cause valve 82 to be spaced apart from hole 68 in lower plate 34. When movable contact 26 disengages contact 78 during opening, the latter is moved upward in guide 72 and valve 82 closes hole or orifice 68. A conductor wire 88 is electrically connected to valve stem 80 exteriorly of interrupter 42.

FIG. 4 schematically shows that when the load break switch is open there are three breaks in series with each other i.e., base 12 and contact 78 are electrically connected; movable contacts 26 and 28 are electrically connected; stationary contacts 90 and 92 are electrically connected; and movable contact 30 and shell 14 are electrically connected. When the load break switch is closed, there is a current path from base 12 to shell 14.

The load break switch hereinbefore described operates as follows: Assume first that the switch is closed as shown in FIG. 2 and that there is current flow through the contacts thereof. In the closed position, the movable bayonet contacts 26, 28 and 30 are in electrical contact with and are depressing the contact members 78, 90 and 92', respectively; the springs 86 are compressed; and the orifices 68 are open.

Now assume that the operating mechanism (not shown) in shell 14 is actuated to efiect opening of the load break switch by moving operating rod 22 upward with respect to FIG. 2. As rod 22 moves upward, piston 20 moves upward to force oil to flow from the interior of tube 18, through the input orifices 62, through the upper chambers .56, and out the exhaust orifices 64 of the three interrupters 42, 44 and 46. There is no substantial flow of oil from the upper chambers 56 through the holes 60 in the partitions 58 into the lower chambers 54 of the interrupters while the bayonet contacts 26, 28 and 30 occupy their respective holes 60.

Upward movement of rod 22 also causes upward movement of the movable contacts 26, 28 and 30 and at the beginning of such upward movement, the springs 86 follow upward movement of their respective contact members 78 until the latter reach the limits of their travel within the guides 72. Upward movement of each contact member 78 is accompanied by upward movement of its associated valve stem 80 and valve plate 82 until the latter closes off its hole 68 in bottom plate 34 so that oil cannot flow therethrough to escape from chamber 54.

Continued upward movement of contact 26 results in disengagement of movable contact 26 from contact 78 and an electric arc is established therebetween. Establishment of the arc is accompanied by vaporization of the oil immediately surrounding the arc and formation of a gas bubble in chamber 54 which tends to increase in size as the arc increases in length. However, since hole 68 is closed and neither the oil nor the gas bubble can escape therethrough, the result is that the gas bubble is kept smaller than it would otherwise be. This is advantageous because it enables the relatively cool body of oil to be closer to the hot central core of the arc than would otherwise be the case thus aiding in its extinguishment.

It is to be understood that sometimes the load break switch is called upon to interrupt exceedingly high currents and the arc produced is such that the vapor pressure within chamber 54 reaches a destructive level. In such cases the pressure within chamber 54 overcomes the closing force of spring 86 and forces valve 82 to open to relieve the pressure within chamber 54 which might otherwise damage the interrupter.

Continued upward movement of contact 26 causes the latter to withdraw through hole 60 in partition 58 and into chamber 56 and the arc extends through hole 60. With hole 60 open, the gas bubble expands therethrough into chamber 56 wherein the continued oil flow through chamber 56 from the pump action of piston 20 acts directly upon the arc and the gas bubble to aid in its extinction. The constriction of passage 64 allows the oil pressure derived from the piston 20 to compress the gas bubble produced by the arc. This compression of the gas bubble brings the oil in more intimate contact with the high temperature core of the arc vaporizing greater quantity of oil and increasing the pressure within chamber 56. The increased pressure creates a further compression of the are increasing its temperature and temperature gradient adjacent exhaust ports 64. The higher temperature gradient enhances thermal conduction from the arc core at the time of current zero improving the interrupting ability of the device. Oil vapor and are by-products are expelled from chamber 56 past the bafiies 66 and out through exhaust opening 64 into the body of oil in housing 10.

After rod 22 has reached its upper limit of travel, and the arcs in each interrupter 42, 44 and 46 have been extinguished, the load break switch is ready to be reclosed to place the switch components in the initial position hereinbefore described. As movable contact 26 depresses contact member 78 valve plate 82 moves away from opening 68 to permit oil to refill chamber 54 in readiness for the subsequent operation.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an electric switch, in combination, a housing containing a body of arc extinguishing fluid, an interrupter casing submerged in said body of fluid, a partition dividing said casing into two chambers but having an opening therethrough, one of said chambers having a valve opening communicating with said body of fluid, said one chamber being sufficiently long so that an are drawn therein can generate a gas bubble therein which has sufficient pressure and volume to permit arc extinction as the arc moves into the other of said chambers, means for circulating fluid from said body of fluid through the other of said chambers, a contact member located Within said one chamber, a movable contact extending into said casing for cooperation with said contact member, said movable contact having on open position wherein it is located in said other chamber and movable to a closed position wherein it extends through said opening in said partition into said one chamber and into engagement with said contact member, and valve means operable to fully close said valve opening when said movable contact disengages said contact memfber whereby the are generated in said one chamber is able to provide a gas bubble having at least a minimum volume and pressure needed to effect are extinction, said valve means being adapted to open said valve opening if pressure within said one chamber exceeds a predetermined value.

2. In an electric switch, in combination, a housing containing a body of arc extinguishing fluid, an interrupter casing submerged in said body of fluid, a partition dividing said casing into two chambers but having an opening therethrough, one of said chambers having a valve opening communicating with said body of fluid, said one chamber being suificiently long so thatan are drawn therein can generate a gas bubble therein which has suflicient pressure and volume to permit arc extinction as the arc moves into the other of said chambers, the other of said chambers having a fluid input opening and a fluid exhaust opening, pump means comprising a cylinder and piston submerged in said body of fluid for circulating fluid through the other of said chambers, said cylinder being connected to the fluid input opening of said other chamber, a contact member located within said one chamber, a movable contact extending into said casing for cooperation with said contact member, said movable contact having an open position wherein it is located in said other chamber and movable in a closed position wherein it extends through said opening in said partition into said one chamber and into engagement with said contact member, means for moving said piston and said movable contact, and valve means operable to fully close said valve opening when said movable contact disengages said contact member whereby the are generated in :said one chamber is able to provide a gas bubble having at least a minimum volume and pressure needed to effect 'are extinction, said valve means being adapted to open said valve opening if pressure Within said one chamber exceeds a predetermined value.

'3. In an electric switch, in combination, a housing containing a body of arc extinguishing fluid, an interrupter casing submerged in said body of fluid, a partition dividing said casing into two chambers but having an opening therethrough, one of said chambers having a valve opening and a hole communicating with said body of fluid, said one chamber being sufficiently long so that an arc drawn therein can generate a gas bubble therein which has sufiicient pressure and volume to permit arc extinction as the arc moves into the other of said chambers, means for circulating fluid from said body of fluid through the other of said chambers, a contact member located within said one chamber, a stem connected to said contact member and extending through said hole in said one chamber, a valve plate connected to said stem outside of said one chamber, biasing means tending to move said contact member, stem and valve plate from one position to another position wherein the valve plate fully closes said valve opening in said one chamber, whereby the arc generated in said one chamber is able to provide a gas bubble having at least a minimum volume and pressure needed to eiTect arc extinction, said biasing means permitting said valve opening to open if pressure within said one chamber exceeds a predetermined value, and a movable contact extending into said casing for cooperation with said contact member, said movable contact having an open position wherein it is located in said other chamber and movable to a closed position wherein it extends through said opening in said partition into said one chamber and into engagement with said contact member to maintain said valve plate in said one position.

4. -In an electric switch, in combination, a housing containing a body of arc extinguishing fluid, an interrupter casing submerged in said body of fluid, a partition dividing said easing into two chambers but having an opening therethrough, one of said chambers having a valve opening and a hole communicating with said body of fluid, said one chamber being suificiently long so that an are drawn therein can generate a gas bubble therein which has sufficient pressure and volume to permit arc extinction as the arc moves into the other of said chambers, the other of said chambers having a fluid input opening and a fluid exhaust opening, pump means comprising a cylinder and a piston submerged in said body of fluid for circulating fluid through the other of said chambers, said cylinder being connected to the fluid input open-ing of said other chamber, a contact member located within said one chamber, a stem connected to said contact member and extending through said hole in said one chamber, a valve plate connected to said stem outside of said one chamber, biasing means tending to move said contact member, stem and valve plate from one position to another posiition wherein the valve plate fully closes said valve opening in said one chamber, whereby the arc generated in said one chamber is able to provide a gas bubble having at least a minimum volume and ressure needed to eifect arc extinction, said biasing means permitting said valve opening to open if pressure within said one chamber exceeds a predetermined value, a movable contact extending into said casing for cooperating with said contact member, said movable contact having an open position wherein it is located in said other chamber and movable to a closed position wherein it extends through said opening in said partition into said one chamber and into engagement with said contact member, and means for moving said piston and said movable contact.

References Cited UNITED STATES PATENTS 2,092,652 9/1937 Merriam 200- 2,445,529 7/ 1948 Leeds 200-150 FOREIGN PATENTS 464,643 4/ 1937 Great Britain.

321,292 6/ 1957 Switzerland.

ROBERT S. MACON, Primary Examiner. 

1. IN AN ELECTRIC SWITCH, IN COMBINATION, A HOUSING CONTAINING A BODY OF ARC EXTINGUISHING FLUID, AN INTERRUPTER CASING SUBMERGED IN SAID BODY OF FLUID, A PARTITION DIVIDING SAID CASING INTO TWO CHAMBERS BUT HAVING AN OPENING THERETHROUGH, ONE OF SAID CHAMBERS HAVING A VALVE OPENING COMMUNICATING WITH SAID BODY OF FLUID, SAID ONE CHAMBER BEING SUFFICIENTLY LONG SO THAT AN ARC DRAWN THEREIN CAN GENERATE A GAS BUBBLE THEREIN WHICH HAS SUFFICIENT PRESSURE AND VOLUME TO PERMIT ARC EXTINCTION AS THE ARC MOVES INTO THE OTHER OF SAID CHAMBERS, MEANS FOR CIRCULATING FLUID FROM SAID BODY OF FLUID THROUGH THE OTHER OF SAID CHAMBERS, A CONTACT MEMBER LOCATED WITHIN SAID ONE CHAMBER, A MOVABLE CONTACT EXTENDING INTO SAID CASING FOR COOPERATION WITH SAID CONTACT MEMBER, SAID MOVABLE CONTACT HAVING ON OPEN POSITION WHEREIN IT IS LOCATED IN SAID OTHER CHAMBER AND MOVABLE TO A CLOSED POSITION WHEREIN IT EXTENDS THROUGH SAID OPENING IN SAID PARTITION INTO SAID ONE CHAMBER AND INTO ENGAGEMENT WITH SAID CONTACT MEMBER, AND VALVE MEANS OPERABLE TO FULLY CLOSE SAID VALVE OPENING WHEN SAID MOVABLE CONTACT DISENGAGES SAID CONTACT MEMBER WHEREBY THE ARC GENERATED IN SAID ONE CHAMBER IS ABLE TO PROVIDE A GAS BUBBLE HAVING AT LEAST A MINIMUM VOLUME AND PRESSURE NEEDED TO EFFECT ARC EXTINCTION, SAID VALVE MEANS BEING ADAPTED TO OPEN SAID VALVE OPENING IF PRESSURE WITHIN SAID ONE CHAMBE EXCEEDS A PREDETERMINED VALUE. 